Description
Quantifying the volumetric performance of machine tools is a vital part of efficient precision engineering. Different metrology techniques are applied to determine the accuracy of the tool path, either directly or indirectly. Extensive industrial and academic efforts have previously been dedicated to establishing models that demonstrate the link between machine errors and deviations from specified geometric features on workpieces in the 3D space. Besides an error model, an uncertainty model is also needed to show both the deviations and variations simultaneously. In other words, the uncertainty model facilitates demonstration of the volumetric performance of a machine tool for manufacturing parts with tight dimensional and geometrical tolerances. Such analysis has not previously been presented. An uncertainty model based on two approaches was developed: a statistical approach (Type A) with the Monte Carlo Method (MCM); and an analytical method using boundary values from statistical analysis of individual measurements. Both methods are novel and currently rely on the scattering of the data measured on a 3-axis vertical machining centre (VMC). The numerical results of the uncertainty estimation for a specific target position, located almost at the central part of this VMC used as a benchmark in this research work, were presented and visually demonstrated according to both MCM and analytical methods. Furthermore, characteristics of MCM and the analytical method in estimating uncertainty were explained and compared to each other.For this research work, an error model based on Rigid Body Theory and Homogeneous Transformation Matrices (HTM) was established for a 3-axis VMC with a kinematic chain of [w X’ Y’ b Z (C) t]. All six error motions of its three linear axes were measured by a laser system according to ISO 230 series. Assembly errors of these axes, mutual squareness errors between axes, were also measured with granite square and dial gauge according to ISO 10791-2:2023. Having all these geometric errors of the machine and synthesising them into HTM calculations results the error vectors in the working volume of this 3-axis machining centre.
| Period | 24 Sept 2024 → 26 Sept 2024 |
|---|---|
| Event title | 3D Metrology conference 2024 |
| Event type | Conference |
| Conference number | 9th |
| Location | Loughborough, United KingdomShow on map |
| Degree of Recognition | International |